Process for manufacturing 1-aminonaphthalene-8-carboxylic acid



Qcorrespon Patented May 1, 1928..

UNITED STATES 1,668,148 PAT NT OFFICE-Q... I

- RICHARD EERZ AND FRITZ SOHULTE, OF FRANKEORT-ON-THE-MAIN, GERMANY, AB-

BIGNORS TO GRASSELLI DYESTUFF CORPORATION, OF NEW YORK, N. Y., A CORPO RATION OF DELAWARE.

PROCESS FOR MANUFACTURING l-AMINONAPETHALENE-8-CARBOXYLIC 80 Drawing. Original application filed July 12, 1926, Serial No. 122,030, and in Germany November 29,

1924. Divided and this application flled May- 9, 1927. Serial lio.- l90,127. I

This application is "a division of our aplplication Serial No. 122,030, filed July 12t 1926, and relates to a new and original rocess for manufacturing the l-aminonap tha- 6 lene-S-carboxylic acid in a pure state with an almost quantitative yield and at comparativel jlow costs. Hitherto thisacid could not e produced in a technical scale.

Our new process consists in allowing an 10 alkalihe acting agent to react at elevated tem eratures on 8-cyannaphthalene-l-sulfo'mc acid. t

The chemical reaction which takes place runs probably as follows:

In the first phase of the reaction probably ON sour odim. sotH- news carrying out our process racti'cally caustic allsalies in aqueous or alco olic solution or alkaline earth metal com ounds,

preferably'milk of lime, may be use either I at ordinary pressure or in a closed vessel at elevated pressure- The starting material for the process, 8- cyannaphthalene-l-sulfonic acid,.is easily obtainable in the usual manner by converting 8-aminona hthalene-l-sulfonic. acid to its the"latter with cuprous cyanide according to the Sandmeyer reaction; It forms a difiicultly soluble sodium salt, which may be thereto of comomn salt or by an uivalent procedure. The free S-cyannapht alene-1 sulfonic acid may be obtained by converting the salt into the diificultly soluble lead salt and setting the acid free. in the usual manner, for instance, by precipitating thelead with the correspondm amount 0 sulfuric acid or hydrogen sul de. -.The 8- cyannaphthalene-Lsulfonic acid is very easily soluble in water and shows a strong- 5 acid reaction. 1 J The new process may be illustrated by-the' pound is ea'sily saponified 'by the action of g diam-compound and treating- I isolated from the filtrate'by. acidifying it. isolated from its solutions by the add1tion the cyanogen group is saponified to the carboxyam1dogroup; the resulting intermediate product, namely the 8;naphthamide-1-sulfonlc acid, can be isolated when carrying out, the reaction. Then, in the second phase, the sulfogroup is split off and a rin is formed,

.namel the inner anhydride of t e l-aminonapht alene-8-carboxylic acid known in the literature as naphthostyr'il. This latter comdilute alkalies to the l-aminonaphthalene 8- carboxylic acid. I

The following formulae illustrate the course of the reactions:

l-amlnona hthalene- When 0 acid.

V naphthoetyrll.

following example, the parts bein by weight and all temperatures in centigraie degreesi Example.

1 part of the sodium salt or of an suitable salt of the 8-0 annaphthalene-l-sul onic' acid. isheatedwit 15 arts of milk of lime of 25 B. for some ours at- 200- -250'in an autoclave, while stirring. The l-amihonaphthalene-S-carboxylic acid, thus formed, remains in solution in the 'form ofits easily soluble calcium-salt. -The mass, is-. diluted with water, filtered. off, and the free acid is We wish it to be understood that, when working in the autoclave, the pressure corre-.

sponds functionall to the tension of the reacting agent and t etemperatur'e applied.

2 I 1,ees,14a-

1-aminonaphthalene-S-carboxylic acid compound which comprises treating a, salti'of 8-cyannaphthalene-I-sulfonic acid with an alkaline earth .metal hydroxide at elevated temperatures not exceeding about 250 C. and under elevated pressure.

3. Process for the manufacture of 'an 1-aminonaphthalene-8-carboxylic acid compound which comprises treatin a salt of S-cyannaphthalene-l-sulfonic aci with milk of lime at elevated temperatures not exceedsure.

- ing about 250 C. and under elevatedrpres- RICHARD HERZ. u FRITZ SCHULTE. 

